The report said Gotti Tedeschi had given copies of his archive to trusted friends, telling them: "If I am killed, the reason for my death is in here."

The archive made up of hundreds of pages, was reportedly seized by prosecutors during raids on Gotti Tedeschi's home and office on Tuesday, as part of a separate inquiry into alleged bribery at defence giant Finmeccanica.

The ex-banker is already under investigation on allegations of money laundering of 23 million euros ($29 million) through the Vatican bank.

He was questioned on Tuesday and Wednesday and is said to be assisting prosecutors.

When he saw plainclothes officers approach his house on Tuesday, Gotti Tedeschi thought they were killers, La Stampa daily reported this week.

Corriere della Sera reported that the archive contained documents "on the management of numerous current accounts through which money of dubious provenance transited."

Gotti Tedeschi was appointed in 2009 and sacked on May 24 by the board of the bank, known as the Institute for Religious Works or IOR, after a long-running dispute with the Vatican Secretary of State Tarcisio Bertone.

A powerful and divisive figure in the Holy See, Bertone is one of the main targets in a series of leaks of confidential documents from the Vatican in recent months.